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SS 347 / 347H Screws Manufacturer & Exporter in India

Explore SS 347 / 347H Screws Manufacturer & Exporter in India manufactured for demanding industrial applications with reliable strength, corrosion resistance and compliance with international standards.
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-196

Min Temp

870

Max Temp

🌡

870

Suitable for continuous service up to approximately 870°C under typical operating conditions.

⚡

620

Typical tensile strength around 620 MPa depending on product form and heat treatment.

🛡

Very Good

Very Good corrosion resistance in a wide range of industrial environments.

⚖

8

Typical density is approximately 8.0 g/cm³.

Product Overview

What are SS 347 / 347H Screws?

SS 347 / 347H screws are austenitic stainless steel fasteners manufactured from stabilized grades UNS S34700 and UNS S34709, conforming to ASTM A193 and ASTM A194 standards. Alloy 347 is stabilized with columbium (niobium) to prevent intergranular corrosion after welding, while 347H features a higher carbon content for enhanced high-temperature strength and creep resistance.

These screws are widely specified for bolted joints in heat exchangers, furnace equipment, and chemical process vessels where resistance to sensitization and scaling at elevated temperatures is critical. SS 347 / 347H screws maintain mechanical integrity and corrosion resistance in continuous service up to 870°C, making them ideal for demanding thermal cycling and oxidizing environments.

Quick Specifications

MaterialStainless Steel 347 / 347H
UNS NumberS34700 / S34709
DIN Number1.4550 / 1.4961
Material StandardASTM A193 / ASTM A194
Screw Standard (Metric)DIN 912 / DIN 933 / ISO 4762
Screw Standard (Inch)ASME B18.3 / ASME B18.2.1
Thread FormISO Metric / UNC / UNF
Diameter RangeM3-M64 / ?"-2½"
Tensile Strength515 MPa (75 ksi) min
Yield Strength205 MPa (30 ksi) min
HardnessMax 223 HB / 95 HRB
? All material certified by NABL-accredited laboratory. PMI and IGC test available on request.

Complete the Fastener Set

Other SS 347 / 347H Fastener Products Available from RealBolt

RealBolt also manufactures the complete SS 347 / 347H fastener range — SS 347 / 347H Bolts, SS 347 / 347H Nuts, SS 347 / 347H Washers, SS 347 / 347H Studs, SS 347 / 347H Threaded Rods — from certified bar stock per ASTM with full EN 10204 MTC 3.1/3.2 documentation and fast Mumbai dispatch.
SS 347 / 347H Bolts
SS 347 / 347H Nuts
SS 347 / 347H Washers
SS 347 / 347H Studs
SS 347 / 347H Threaded Rods

Technical Data

SS 347 / 347H Screws Dimensions, Sizes & Thread Standards

SS 347 / 347H Screws are available in metric M6–M100 and inch ¼″–4″ as standard. Per DIN 912 (socket head cap), DIN 933 (hex full thread), ISO 4762. Custom lengths in 5mm increments. Inch dimensions available per ASME B18.3 and B18.2.1.

Socket Head Cap Screw Dimensions - Metric (DIN 912 / ISO 4762)

Size (M)Pitch (mm)Head Dia (mm)Head Ht (mm)Min L (mm)Max L (mm)
M30.55.53.0650
M40.77.04.0860
M50.88.55.01070
M61.010.06.01280
M81.2513.08.016100
M101.516.010.020120
M121.7518.012.025150
M162.024.016.030200
M202.530.020.035250
M243.036.024.040300
M303.545.030.050400
M364.054.036.060500
M424.563.042.070600
M485.072.048.080700
M565.584.056.090800
M646.096.064.0100900

Dimensional & Material Standards

StandardCoversThread
DIN 912Socket head cap screwsMetric
DIN 933Hex screws, full threadMetric
ISO 4762Socket head cap screwsMetric
ASME B18.3Socket cap screwsUNC/UNF
ASME B18.2.1Hex screwsUNC/UNF
Material StandardRequirement
ASTM A193Bolting material for high temp/pressure
ASTM A194Heavy hex nuts
EN 10204 3.1Mill test certificate
EN 10204 3.2TPI-witnessed MTC

Material Chemistry

SS 347 / 347H Chemical Composition

SS 347 / 347H Screws are manufactured from an iron-chromium-nickel alloy with chromium (16–26%), nickel (8–28%), and grade-specific molybdenum additions per ASTM and ASTM A193/A194. Chromium content governs the self-healing passive oxide film; molybdenum (2–6%) enhances chloride pitting resistance; and carbon content determines sensitization risk in welded assemblies.

Chemical Composition per ASTM A193/A194

Element347 (%)347H (%)
Chromium (Cr)17.0-19.017.0-19.0
Nickel (Ni)9.0-13.09.0-13.0
Carbon (C)0.08 max0.04-0.10
Manganese (Mn)2.00 max2.00 max
Silicon (Si)1.00 max1.00 max
Phosphorus (P)0.045 max0.045 max
Sulfur (S)0.030 max0.030 max
Niobium (Nb)10xC-1.08xC-1.0
Iron (Fe)BalanceBalance
? All heats verified by NABL-accredited spectrometry. PMI and IGC test available on request.

Why SS 347 / 347H Alloy Composition Matters for Screws

Nb Stabilization — Intergranular Corrosion Resistance
Niobium (columbium) stabilizes SS 347 / 347H, preventing chromium carbide precipitation at grain boundaries during welding or high-temperature service. This ensures screws retain corrosion resistance even after repeated thermal cycling.
347H — High Carbon for Creep Strength
The higher carbon content in 347H improves creep resistance and mechanical strength at temperatures above 500°C, making these screws ideal for furnace and heat exchanger applications.
Austenitic Structure — Ductility & Fabrication
The austenitic matrix provides excellent ductility, formability, and toughness, allowing SS 347 / 347H screws to be cold-formed and machined to precise tolerances for critical bolted joints.

Fastener Performance

SS 347 / 347H Screws Mechanical Properties & Torque Reference

The table below lists mechanical properties and torque reference for SS 347 / 347H Screws per ASTM. SS 347 / 347H screws achieve 620 MPa tensile strength, with hardness, yield, and elongation values verified by NABL-accredited testing and reported in the EN 10204 MTC.

Screw SizeDry (Nm)Lubricated (Nm)Clamp Load (kN)
M8252010
M10493916
M12856823
M1621016845
M2041032871
M24710568103
M3014001120167
M3624001920241
?? Anti-galling: Use molybdenum-based or PTFE anti-seize. Lubricated values assume K=0.16. Avoid copper-based anti-seize for high-temperature service.

Industry Applications

SS 347 / 347H Screws Applications — Industries & End Uses

SS 347 / 347H Screws from RealBolt are specified across food and dairy, pharmaceutical, marine, chemical processing, and oil and gas where very good corrosion resistance and 620 MPa tensile strength are required for reliable fastener performance. Click each industry below for detailed application examples.
SS 347 / 347H screws are widely used in heat exchanger tube sheets, reactor vessel closures, and process piping flanges in refineries and petrochemical plants. Their resistance to polythionic acid stress corrosion and high-temperature scaling makes them ideal for sulfur-rich and oxidizing environments.
Socket head and hex screws for furnace linings, radiant tube supports, and burner assemblies where repeated thermal cycling and exposure to oxidizing atmospheres demand stabilized stainless steel fasteners.
Used in chemical reactors, acid production towers, and pressure vessel manways where resistance to intergranular corrosion and sensitization is critical for long-term reliability.
Screws for boiler tube sheets, superheater header connections, and steam piping in fossil fuel and waste-to-energy plants, where high-temperature strength and oxidation resistance are required.

SS 347 / 347H Screws Standards & International Certifications

SS 347 / 347H Screws from RealBolt Engineering Industries are manufactured to internationally recognised fastener dimensional standards covering thread form, tolerances, strength grades, and quality requirements. Every batch ships with EN 10204 MTC 3.1/3.2, IS 12427 compliance, ISO 3506 material certification, NACE MR0175, and PMI (XRF) reports — available on request for all orders.
Standards
DIN 84 DIN 85 DIN 912 DIN 913 DIN 914 DIN 915 DIN 916 DIN 6912 DIN 7984 DIN 7985 DIN 7991 DIN 965 DIN 966 DIN 967 ISO 4762 ISO 10642 ISO 14579 ASME B18.3 ASME B18.6.3 EN ISO 4762 IS 1363 IS 1367 IS 12427 SAE J933
Certifications
ISO 9001:2015PED 2014/68/EUNABL LabEN 10204 3.1 / 3.2

Buy SS 347 / 347H Screws from India's Leading Manufacturer — Get a Competitive Quote Today

Partner with RealBolt — India’s leading manufacturer of certified SS 347 / 347H Screws — for competitive pricing, EN 10204 MTC 3.1/3.2 documentation, and fast Mumbai dispatch. Standard sizes are ex-stock; custom dimensions accepted with 2–3 week lead time. Request your quote today.
022-6743-7972
+91 90226 36025
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Answers for Buyers

SS 347 / 347H Screws — Frequently Asked Questions

Browse expert answers to common questions about SS 347 / 347H Screws from RealBolt — covering ASTM A193/A194 grades, chloride resistance, temperature limits, sensitization, sizes, and MTC documentation. Contact our technical team directly for project-specific guidance on SS 347 / 347H screws selection and pricing.
What screw standards are available for SS 347 / 347H screws?
What anti-seize should I use on SS 347 / 347H screws?
Are SS 347 / 347H screws suitable for high-temperature furnace applications?
What is the minimum order quantity (MOQ) for SS 347 / 347H screws?

Industrial Cities We Serve:

  • Ahmedabad
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  • Chennai
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  • Greater Noida
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